What Is a Keto Diet?

The keto diet has revolutionized how many people eat and changed how they produce and consume energy. 

Short for ketogenic, the keto diet limits your carbohydrate intake to less than 50 grams per day.

In the average American diet, carbohydrates comprise 45% to 65% of our caloric intake. A classic calorie restriction diet limits the number of calories while balancing your protein, carbohydrate, and fat intake. However, cutting carbohydrates distinguishes the keto diet from typical diets and prolonged fasting.

During the ketogenesis process, the body creates ketone bodies, which can be burned to generate energy when glucose and carbohydrates aren’t available. While ketogenesis regularly occurs to supplement energy production, it’s not the norm.

The keto diet’s goal is to force your body into ketosis through ketogenesis as opposed to the typical carbohydrate pathway, or glycogenolysis. This switch can impact the body in several ways: 1) Alleviate depressive symptoms, 2) Stabilize blood sugar levels, and 3) Inhibit inflammation.

How Does the Keto Diet Affect the Body?

The keto diet is used to shed unwanted pounds, but there are cognitive effects as well. 

A scientific review conducted by the Radboud University Medical Center found that the keto diet had broad effects on the brain because ketone bodies are the preferred source of energy for the brain while fasting. In mice with Alzheimer’s disease, a keto diet was found to improve performance on mental tasks. In mice with autism spectrum disorder, a keto diet was found to increase social activities.

The increase of ketones in the body may lead to cognitive benefits in healthy individuals as well. By indirectly increasing brain-derived neurotrophic factor (BDNF), ketones stimulate learning and memory capacity by increasing the number of mitochondria, synaptic plasticity, and cellular stress resistance. A change in ketones also affects the mammalian target of the rapamycin (mTOR) pathway that regulates the metabolism and body, mitigating harmful oxidative stress.

While the keto diet’s impact on the body and brain is beneficial, there are some unintended consequences.

In the short term, it can take multiple weeks for your body to adjust to processing primarily fats and proteins for energy. As you transition, your body may experience “keto flu” which includes fatigue, headache, nausea, constipation, and vomiting. To minimize these symptoms, don’t go completely carb-free overnight. Instead, slowly reduce your total carb intake over several days.

Though the keto diet is widely believed to be great for burning fat, it can also burn muscle mass. By training your body to eat fat and protein, your body can consume itself because it’s primarily made up of fat and protein. You can partially offset this by eating more protein and lifting weights regularly.

Since one of the ways your body rids itself of ketones is through your breath, going on a keto diet may cause ketone-powered bad breath. Known as “keto breath,” it may smell like acetone in nail polish remover. Some describe it as metallic or fruity, typically it is unpleasant. To control keto breath, try cutting back on your protein intake.

Finally, the keto diet can strain your liver as it generates ketone bodies from stored fat and the fat in your new diet. However, avoiding carbohydrates will keep your liver healthy, as will omega-3s found in fish and nuts.

What Does “Net Carbs” Mean?

“Net carbs” refers to the total number of carbohydrates your body can process into energy. Because fiber is a carbohydrate that the body cannot digest, some keto diet followers subtract their fiber intake from their total carbohydrate intake to calculate their net carbs. 

When following a keto diet, you can track how many carbohydrates you eat as a total or as net carbs. Followers of the net carbohydrates method keep their consumption under 50 grams. It’s a less strict method of following keto that emphasizes fiber in your diet.

What Fruits and Vegetables Can You Eat On a Keto Diet?

When many people adopt the keto diet, they end up eating much more healthily than they ever have because they start thinking very intentionally about what they put in their bodies. 

People on the keto diet often eat a lot of vegetables because they are low in carbs, contain fiber, and make you feel full. This fiber helps your digestive system work, preventing an upset system and constipation from consuming so much meat and fat.

While most vegetables are fine for a keto diet because they are primarily made of water, some contain significant amounts of starch and sugar. In general, leafy greens are fine but root vegetables should be avoided. 

Keto-friendly vegetables:

• Lettuce
• Mushrooms
• Avocados
• Cucumber
• Asparagus
• Zucchini
• Green beans
• Cauliflower
• Cabbage
• Broccoli

Vegetables to avoid on a keto diet:

• Sweet corn
• Potatoes
• Beets
• Peas
• Onion
• Yam
• Sweet potato
• Yam
• Cassava
• Butternut squash

It’s all right to eat the latter vegetables in small portions, staying below 50 grams of daily carbohydrates.

In addition to these vegetables, a few fruits have low enough sugar content to be included in a keto diet if you control your portion size. The best options include tomatoes, starfruit, watermelon, and strawberries.

Is the Keto Diet Dangerous?

Short-term ketosis is not dangerous at all. Going into ketosis is a natural process. You do it in your sleep when your body is temporarily fasting.

There is a dangerous condition that involves an overabundance of ketone bodies called ketoacidosis, but this is typically caused by extreme alcoholism, starvation, or diabetes, not by following a keto diet.

Finally, following the keto diet for extended periods can put extra strain on your liver and kidneys to generate ketone bodies and process the byproducts of their metabolism. Eat healthy fats and exercise to counteract this stress.

As with any diet, consult with your primary care physician before starting. Your doctor can monitor your progress and flag any adverse effects for treatment.